Return-Path: linux-nfs-owner@vger.kernel.org Received: from fieldses.org ([174.143.236.118]:38776 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755589Ab3BGPCP (ORCPT ); Thu, 7 Feb 2013 10:02:15 -0500 Date: Thu, 7 Feb 2013 10:02:13 -0500 To: Chuck Lever Cc: bfields@fields.org, linux-nfs@vger.kernel.org Subject: Re: [PATCH] SUNRPC: Refactor nfsd4_do_encode_secinfo() Message-ID: <20130207150213.GC3222@fieldses.org> References: <20130201220308.13518.82164.stgit@seurat.1015granger.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20130201220308.13518.82164.stgit@seurat.1015granger.net> From: "J. Bruce Fields" Sender: linux-nfs-owner@vger.kernel.org List-ID: On Fri, Feb 01, 2013 at 05:43:44PM -0500, Chuck Lever wrote: > Clean up. This matches a similar API for the client side, and > keeps ULP fingers out the of the GSS mech switch. > > Signed-off-by: Chuck Lever > Acked-by: J. Bruce Fields > --- > > Bruce- > > This version of the patch follows the existing logic in > nfsd4_do_encode_secinfo(): If the RPC layer can't find GSS info > that matches an export security flavor, it assumes the flavor is > not a GSS pseudoflavor, and simply puts it on the wire. > > However, if the below XDR encoding logic is given a legitimate GSS > pseudoflavor but the RPC layer says it does not support that > pseudoflavor for some reason, then we leak GSS pseudoflavor numbers > onto the wire. > > I confirmed this happens by blacklisting rpcsec_gss_krb5, then > attempted a client transition from the pseudo-fs to a Kerberos-only > share. The client received a flavor list containing the Kerberos > pseudoflavor numbers, rather than GSS tuples. > > The encoder logic can check that each pseudoflavor is less than > MAXFLAVOR before writing it into the buffer, to prevent this. But > after "nflavs" is written into the XDR buffer, the encoder can't > skip writing flavor information into the buffer when it discovers > the RPC layer doesn't support that flavor. > > Is there some way of writing "nflavs" into the XDR buffer after > the loop that writes the flavor information is complete? Yes, you can save a pointer and then go back and fill that in--see encode_fattr for an example. --b. > > What if "nflavs" turns out to be zero? RFC 3530bis, 15.33.4 does > not explicitly say what should be done if the array of security > mechanisms for that client and file handle contains zero items. > > Or is there a better way to handle this situation? Also, should we > care about this scenario? > > > fs/nfsd/nfs4xdr.c | 24 +++++++++++------------ > include/linux/sunrpc/auth.h | 2 ++ > include/linux/sunrpc/gss_api.h | 3 +++ > net/sunrpc/auth.c | 34 +++++++++++++++++++++++++++++++++ > net/sunrpc/auth_gss/auth_gss.c | 1 + > net/sunrpc/auth_gss/gss_mech_switch.c | 34 +++++++++++++++++++++++++++++++-- > 6 files changed, 83 insertions(+), 15 deletions(-) > > diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c > index 0dc1158..424f5a2 100644 > --- a/fs/nfsd/nfs4xdr.c > +++ b/fs/nfsd/nfs4xdr.c > @@ -3127,10 +3127,9 @@ nfsd4_encode_rename(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_ > > static __be32 > nfsd4_do_encode_secinfo(struct nfsd4_compoundres *resp, > - __be32 nfserr,struct svc_export *exp) > + __be32 nfserr, struct svc_export *exp) > { > - int i = 0; > - u32 nflavs; > + u32 i, nflavs; > struct exp_flavor_info *flavs; > struct exp_flavor_info def_flavs[2]; > __be32 *p; > @@ -3161,30 +3160,29 @@ nfsd4_do_encode_secinfo(struct nfsd4_compoundres *resp, > WRITE32(nflavs); > ADJUST_ARGS(); > for (i = 0; i < nflavs; i++) { > - u32 flav = flavs[i].pseudoflavor; > - struct gss_api_mech *gm = gss_mech_get_by_pseudoflavor(flav); > + struct rpcsec_gss_info info; > > - if (gm) { > + if (rpcauth_get_gssinfo(flavs[i].pseudoflavor, &info) == 0) { > RESERVE_SPACE(4); > WRITE32(RPC_AUTH_GSS); > ADJUST_ARGS(); > - RESERVE_SPACE(4 + gm->gm_oid.len); > - WRITE32(gm->gm_oid.len); > - WRITEMEM(gm->gm_oid.data, gm->gm_oid.len); > + RESERVE_SPACE(4 + info.oid.len); > + WRITE32(info.oid.len); > + WRITEMEM(info.oid.data, info.oid.len); > ADJUST_ARGS(); > RESERVE_SPACE(4); > - WRITE32(0); /* qop */ > + WRITE32(info.qop); > ADJUST_ARGS(); > RESERVE_SPACE(4); > - WRITE32(gss_pseudoflavor_to_service(gm, flav)); > + WRITE32(info.service); > ADJUST_ARGS(); > - gss_mech_put(gm); > } else { > RESERVE_SPACE(4); > - WRITE32(flav); > + WRITE32(flavs[i].pseudoflavor); > ADJUST_ARGS(); > } > } > + > out: > if (exp) > exp_put(exp); > diff --git a/include/linux/sunrpc/auth.h b/include/linux/sunrpc/auth.h > index 476e97c..c34ac17 100644 > --- a/include/linux/sunrpc/auth.h > +++ b/include/linux/sunrpc/auth.h > @@ -105,6 +105,7 @@ struct rpc_authops { > void (*pipes_destroy)(struct rpc_auth *); > int (*list_pseudoflavors)(rpc_authflavor_t *, int); > rpc_authflavor_t (*info2flavor)(struct rpcsec_gss_info *); > + int (*flavor2info)(rpc_authflavor_t, struct rpcsec_gss_info *); > }; > > struct rpc_credops { > @@ -140,6 +141,7 @@ int rpcauth_unregister(const struct rpc_authops *); > struct rpc_auth * rpcauth_create(rpc_authflavor_t, struct rpc_clnt *); > void rpcauth_release(struct rpc_auth *); > rpc_authflavor_t rpcauth_get_pseudoflavor(rpc_authflavor_t, struct rpcsec_gss_info *); > +int rpcauth_get_gssinfo(rpc_authflavor_t, struct rpcsec_gss_info *); > int rpcauth_list_flavors(rpc_authflavor_t *, int); > struct rpc_cred * rpcauth_lookup_credcache(struct rpc_auth *, struct auth_cred *, int); > void rpcauth_init_cred(struct rpc_cred *, const struct auth_cred *, struct rpc_auth *, const struct rpc_credops *); > diff --git a/include/linux/sunrpc/gss_api.h b/include/linux/sunrpc/gss_api.h > index e8299b2..dc1e51b 100644 > --- a/include/linux/sunrpc/gss_api.h > +++ b/include/linux/sunrpc/gss_api.h > @@ -132,6 +132,9 @@ void gss_mech_unregister(struct gss_api_mech *); > /* Given a GSS security tuple, look up a pseudoflavor */ > rpc_authflavor_t gss_mech_info2flavor(struct rpcsec_gss_info *); > > +/* Given a pseudoflavor, look up a GSS security tuple */ > +int gss_mech_flavor2info(rpc_authflavor_t, struct rpcsec_gss_info *); > + > /* Returns a reference to a mechanism, given a name like "krb5" etc. */ > struct gss_api_mech *gss_mech_get_by_name(const char *); > > diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c > index ec18827..4c551f9 100644 > --- a/net/sunrpc/auth.c > +++ b/net/sunrpc/auth.c > @@ -158,6 +158,40 @@ rpcauth_get_pseudoflavor(rpc_authflavor_t flavor, struct rpcsec_gss_info *info) > EXPORT_SYMBOL_GPL(rpcauth_get_pseudoflavor); > > /** > + * rpcauth_get_gssinfo - find GSS tuple matching a GSS pseudoflavor > + * @pseudoflavor: GSS pseudoflavor to match > + * @info: rpcsec_gss_info structure to fill in > + * > + * Returns zero and fills in "info" if pseudoflavor matches a > + * supported mechanism. > + */ > +int > +rpcauth_get_gssinfo(rpc_authflavor_t pseudoflavor, struct rpcsec_gss_info *info) > +{ > + rpc_authflavor_t flavor = pseudoflavor_to_flavor(pseudoflavor); > + const struct rpc_authops *ops; > + int result; > + > + if ((ops = auth_flavors[flavor]) == NULL) > + request_module("rpc-auth-%u", flavor); > + spin_lock(&rpc_authflavor_lock); > + ops = auth_flavors[flavor]; > + if (ops == NULL || !try_module_get(ops->owner)) { > + spin_unlock(&rpc_authflavor_lock); > + return -ENOENT; > + } > + spin_unlock(&rpc_authflavor_lock); > + > + result = -ENOENT; > + if (ops->flavor2info != NULL) > + result = ops->flavor2info(pseudoflavor, info); > + > + module_put(ops->owner); > + return result; > +} > +EXPORT_SYMBOL_GPL(rpcauth_get_gssinfo); > + > +/** > * rpcauth_list_flavors - discover registered flavors and pseudoflavors > * @array: array to fill in > * @size: size of "array" > diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c > index 4522297..ade24b2 100644 > --- a/net/sunrpc/auth_gss/auth_gss.c > +++ b/net/sunrpc/auth_gss/auth_gss.c > @@ -1630,6 +1630,7 @@ static const struct rpc_authops authgss_ops = { > .pipes_destroy = gss_pipes_dentries_destroy, > .list_pseudoflavors = gss_mech_list_pseudoflavors, > .info2flavor = gss_mech_info2flavor, > + .flavor2info = gss_mech_flavor2info, > }; > > static const struct rpc_credops gss_credops = { > diff --git a/net/sunrpc/auth_gss/gss_mech_switch.c b/net/sunrpc/auth_gss/gss_mech_switch.c > index c8da89e..a8d6ee5 100644 > --- a/net/sunrpc/auth_gss/gss_mech_switch.c > +++ b/net/sunrpc/auth_gss/gss_mech_switch.c > @@ -240,8 +240,6 @@ gss_mech_get_by_pseudoflavor(u32 pseudoflavor) > return gm; > } > > -EXPORT_SYMBOL_GPL(gss_mech_get_by_pseudoflavor); > - > /** > * gss_mech_list_pseudoflavors - Discover registered GSS pseudoflavors > * @array: array to fill in > @@ -314,6 +312,38 @@ rpc_authflavor_t gss_mech_info2flavor(struct rpcsec_gss_info *info) > return pseudoflavor; > } > > +/** > + * gss_mech_flavor2info - look up a GSS tuple for a given pseudoflavor > + * @pseudoflavor: GSS pseudoflavor to match > + * @info: rpcsec_gss_info structure to fill in > + * > + * Returns zero and fills in "info" if pseudoflavor matches a > + * supported mechanism. Otherwise a negative errno is returned. > + */ > +int gss_mech_flavor2info(rpc_authflavor_t pseudoflavor, struct rpcsec_gss_info *info) > +{ > + struct gss_api_mech *gm; > + int i; > + > + gm = gss_mech_get_by_pseudoflavor(pseudoflavor); > + if (gm == NULL) > + return -ENOENT; > + > + for (i = 0; i < gm->gm_pf_num; i++) { > + if (gm->gm_pfs[i].pseudoflavor == pseudoflavor) { > + memcpy(info->oid.data, gm->gm_oid.data, gm->gm_oid.len); > + info->oid.len = gm->gm_oid.len; > + info->qop = gm->gm_pfs[i].qop; > + info->service = gm->gm_pfs[i].service; > + gss_mech_put(gm); > + return 0; > + } > + } > + > + gss_mech_put(gm); > + return -ENOENT; > +} > + > u32 > gss_pseudoflavor_to_service(struct gss_api_mech *gm, u32 pseudoflavor) > { > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html